A LAN monitor control unit causes a trap processing part to check a likelihood of communication by a LAN in a predetermined cycle. When the LAN communication is enabled, a trap processing part transmits a trap issued at a trap issue section to a manager via the LAN. When the LAN communication is not enabled, the trap issued at the trap issue section is saved in a local buffer until the LAN communication becomes enabled, and as soon as the LAN communication becomes enabled, the trap saved in the local buffer is transmitted to the manager via the LAN to thereby minimize a loss of the trap transmitted from an agent to the manager when the LAN communication is not enabled.    [Patent Document 1] Japanese Laid-open Patent Publication No. 2004-80397